As is well known, one significant factor in determining the life of a gas turbine engine revolves about the ability of the turbine nozzle to stand up to the temperatures of the hot gases of combustion that the nozzle receives from the engine combustor and directs against the turbine wheel. Too high temperatures will result in metal fatigue, while non-uniform temperatures will result in thermally generated stresses which will, over a period of time, literally pull the nozzle apart.
While there are many ways of attacking these problems, one approach focuses itself on the cooling of the vanes that make up a typical nozzle. Cooling the vanes typically involves locating one or more passages within each vane that pass a cooling fluid through such a passage. Quite frequently, a variety of apertures extend from the coolant passages within the vanes to the surfaces of the vanes so that a coolant, typically compressed air from the compressor section of the engine, is discharged into the stream of gases flowing to the turbine wheel. Many of these proposals are extremely complicated and expensive to implement due to the need for specialized conduits, the forming of a multiplicity of apertures and the like.
In the previously identified co-pending application, the details of which are herein incorporated by reference, there is disclosed a simplified means of cooling the vanes in a turbine nozzle. In particular, according to one embodiment disclosed therein, each vane, near its leading edge, includes a single internal passage that is connected to the discharge side of the turbine engine compressor to receive compressed air therefrom. An opening extends from the passage to the leading edge and opens thereat so that coolant first flows through each vane to cool the same by conduction and then is discharged at the leading edge to flow past the sides of the vanes to provide a further cooling effect.
The present invention is intended to be an improvement on the invention disclosed in the previously identified, prior application.